Prior art discloses operating devices such as variable capacitors. However, all such devices relate to the field of radio and are directed to structure which provides adjustment of capacitor plates but do not interrupt current. These types of devices are not as adaptable to being serviced as are vacuum switches, and they are also more costly to manufacture. Combined devices are exemplified as disclosed in U.S. Pat. No. 3,541,284, and as there shown, the capacitors are embedded in the wall of the envelope. Thus, it is apparent that these devices cannot serve as shield members.
Normally vacuum switches are used in series and when so used a means must be provided to assure that the total voltage is shared equally by all of the switches in the series as far as may be practical. Typically a 69 kV capacitor switch will utilize four vacuum switches in series. These are paralleled by individual capacitors of approximately 200 pF, which are sufficiently large to assure proper voltage distribution for the 69 kV switch. Since these capacitors are costly and also require annual checks a less costly and more reliable means is desirable.
In accordance with the present invention, there is provided a vacuum switch which incorporates integral capacitors which are also effective as shields. The capacitors occupy the same space as the interrupter contacts and thus provide a compact, high capacitance vacuum switch.